Abstract

The introduction of Photovoltaic Cells (PVC) and their inverters into a power distribution network may cause high frequency components to be generated in addition to the required 50 Hz. Many electricity suppliers will be installing smart meters during the next few years [1]. It is likely that these smart meters communicate with the electricity suppliers' control centre using power line carrier (PLC) communications. A suitable frequency range for this PLC is 50 kHz to 150 kHz. Current measurements of a typical PVC, are presented in this paper and they show a very large current spike occurring at a 1 second period, a large current at 16 kHz, being related to the switching frequency of the inverter, in addition to noise like currents at 112 kHz. The energy associated with this 112 kHz current is larger than the receiver sensitivity of PLC receivers and requires the transmitted power levels for the PLC signals for smart meters to be increased for reliable operation. These unwanted signals produced by the PVC will pass through distribution transformers and may thus effect network stability, network losses and the ability to control smart meters.
The authors are developing a communication system for SWER lines, so that smart metering, fault detection and enhanced network control can be applied to SWER lines. As part of this ERGON sponsored work a high frequency model of a 10 kVA and 25 kVA power transformer was developed. In this paper, this model is used to investigate if PVC inverter spurii will determine noise levels at 230 V or are likely to propagate through the distribution network.